The maturity level of part of the skeleton can be assessed from radiographs in the living. The information gained (bone age or skeletal age) is important to human biologists because of its use in describing populations and understanding fundamental aspects of skeletal elongation and maturation. Also this measure is of great importance to pediatricians, endocrinologists, orthopedists and orthodontists. Until recently, skeletal age had to be assessed using an atlas of "standards." Recently, as a result of work done under this grant, the RWT method has become available for the knee; a somewhat similar, but more restricted, method has been developed by Tanner. It is proposed to complete the RWT method for the hand-wrist, to begin the development of a corresponding method for the foot-ankle, and to make a pilot study of the maturation of the vertebral column. The RWT hand-wrist method will be calibrated for the total United States population, its replicability studied, the errors of individual estimates calculated and comparisons made with other assessment methods applied to the same radiographs. The RWT knee method will be extended to younger ages and the utility of RWT knee and hand-wrist skeletal ages, when applied in the RWT stature prediction method, will be examined.